钢箱梁桥梁用梯形闭口加劲肋的辊弯成型技术

综述了钢箱梁桥梁用梯形闭口加劲肋在辊弯成型过程中的主要控制技术,提出了钢箱梁桥梁用梯形闭口加劲肋的常用规格和技术要求的建议。     

人文学科实验室建设与复合型人才培养探析

人文学科实验室的构建,既有利于激发学生对于学习的兴趣和渴望,也为复合型人才的培养营造了良好的学习环境。该文从文科实验室的建设、复合型人才的培养和文科实验室建设对复合型人才培养的效用三方面来探析文科实验室建设与复合型人才培养之间的内部联系,提出优化校园学习环境、坚持以学生为本、强化锻炼学生的实践能力、推动校外人文学科教学基地合作等具体措施。     

基于数字多波束形成的比幅测向法

面对现代战争的超视距要求,需要通信侦察装备具有很高的侦测灵敏度,尤其是侦测各种天波、散射及旁瓣信号。为此,提出将数字波束形成算法与比幅测向相结合,在空域与频域同时处理阵列信号,以此来提高系统的测向灵敏度和测向精度,仿真结果表明该方法要明显优于相位干涉仪测向法。     

Application of digital image correlation to full-field measurement of shrinkage strain of dental composites

Objectives: Polymerization shrinkage of dental composites remains a major concern in restorative dentistry because it can lead to micro-cracking of the tooth and debonding at the tooth-restoration interface. The aim of this study was to measure the full-field polymerization shrinkage of dental composites using the optical digital image correlation (DIC) method and to evaluate how the measurement is influenced by the factors in experiment setup and image analysis. Methods: Four commercial dental composites, Premise Dentine, Z100, Z250 and Tetric EvoCeram, were tested. Composite was first placed into a slot mould to form a bar specimen with rectangular-section of 4 mm mm, followed by the surface painting to create irregular speckles. Curing was then applied at one end of the specimen while the other part were covered against curing light for simulating the clinical curing condition of composite in dental cavity. The painted surface was recorded by a charge-coupled device (CCD) camera before and after curing. Subsequently, the volumetric shrinkage of the specimen was calculated with specialist DIC software based on image cross correlation. In addition, a few factors that may influence the measuring accuracy, including the subset window size, speckle size, illumination light and specimen length, were also evaluated. Results: The volumetric shrinkage of the specimen generally decreases with increasing distance from the irradiated surface with a conspicuous exception being the composite Premise Dentine as its maximum shrinkage occurred at a subsurface distance of about 1 mm instead of the irradiated surface. Z100 had the greatest maximum shrinkage strain, followed by Z250, Tetric EvoCeram and then Premise Dentine. Larger subset window size made the shrinkage strain contour smoother. But the cost was that some details in the heterogeneity of the material were lost. Very small subset window size resulted in a lot of noise in the data, making it difficult to discern the general pattern in the strain distribution. Speckle size did not seem to have obvious effect on the volumetric shrinkage strain along specimen length; however, larger speckles resulted in higher level of noise or heterogeneity in the shrinkage distribution. Compared with bright illumination, dimmer lighting produced larger standard deviations in the measured shrinkage, indicating a higher level of noise. The longer the specimen, the greater was the rate of reduction with distance from the irradiated surface, especially for the longitudinal strain. Significance: The image correlation method is capable of producing full-field polymerization shrinkage of dental composites. The accuracy of the measurements relies on selection of optimal parameters in experimental setup and DIC analysis.     

Development of lanthanum strontium cobalt ferrite composite cathodes for intermediate- to low-temperature solid oxide fuel cells

Solid oxide fuel cells(SOFCs) offer high energy conversion,low noise,low pollutant emission,and low processing cost.Despite many advantages,SOFCs face a major challenge in competing with other types of fuel cells because of their high operating temperature.The necessity to reduce the operational temperature of SOFCs has led to the development of research into the materials and fabrication technology of fuel cells.The use of composite cathodes significantly reduces the cathode polarization resistance and expands the triple phase boundary area available for oxygen reduction.Powder preparation and composite cathode fabrication also affect the overall performance of composite cathodes and fuel cells.Among many types of cathode materials,lanthanum-based materials such as lanthanum strontium cobalt ferrite(La1-xSrxCo1-yFeyO3- have recently been discovered to offer great compatibility with ceria-based electrolytes in performing as composite cathode materials for intermediate-to low-temperature SOFCs(IT-LTSOFCs).This paper reviews various ceria-based composite cathodes for IT-LTSOFCs and focuses on the aspects of progress and challenges in materials technology.     

Speech and the learning process

The semiotic assumption that language is a system of symbols, signals, or signs minimally entails a commitment to the position that there are two worlds, one linguistic and the ether non‐linguistic, and that they are related by some sort of representation. This essay challenges this view insofar as it purports to account for all language functions. It offers a complementary idea that emerges from the writings of Heidegger, Gadamer, and Buber: that language in spoken conversation is often constitutive, not merely instrumental and representional.     

Unpacking child-centredness: A history of meanings

This paper examines the historical development of the term 'child-centred' in the discourse of early schooling in America. The discussion begins with the founder of the kindergarten, Friedrich Froebel, and traces the development of the kindergarten in the US until the 1930s. We explore how underlying meanings of the term child-centredness have changed - which were lost and which survived by tracing the educational and philosophical currents of each historical context. The term balances on many layers of complex and sometimes contradictory meanings that have been forged over the years by competing interest groups, each appropriating the term and, adding to and taking away from the existing meaning, moulding it to their own purposes. In the process, some underlying meanings were lost, others were added. Meanings were changed and then shared within and sometimes across groups. The term has masked complex and contradictory underlying assumptions about children and their learning and development that should be addressed.     

消费者剩余与生产者剩余的博弈及其对体育产业综合效益的影响

从博弈论的角度,阐释了体育消费者剩余的重要意义和影响因素。指出体育产业作为独立的生产者和社会的合作者,在谋求产业利润最大化的同时必须重视对社会的贡献,即尊重和关怀消费者,合理让渡生产者剩余给消费者剩余,达到生产者剩余与消费者剩余的共生,实现体育产业社会效益与经济效益的最大化。     

高校体育专业排球普修课运用"组合"模式教学的实验研究

通过教学实验和问卷调查,对"组合"教学模式在高校排球教学中的教学效果进行了研究,证明该模式能够明显提高教学质量,并从理论分析的角度论证了该模式的显著优势。     

城市居民羽毛球消费行为形成因素的关系

依托"霍华德·谢思消费行为理论",对杭州市羽毛球活动消费行为及影响因素进行调查,旨在探索羽毛球活动参与行为的形成过程.550名羽毛球场馆活动参与者完成了一个根据该理论自编的"行为因素"问卷.调查结果表明,羽毛球活动消费行为在时间、频率、经历、支出与刺激因素、外在因素、内在因素、反应因素都存在着直接或间接关系.研究认为,"霍华德·谢思消费行为理论"只是部分地解释羽毛球活动消费行为,基于此,文章对羽毛球活动消费行为的特殊性进行了讨论,构建了羽毛球参与者消费行为过程的理论模型.